Tag: Neutrik

Electricity and our Saurer 2DM

This is sort of a never ending story for me – just as the installation of our workshop container on the truck bed by our trusty mechanic which has been “in the making” since October 2022.

It is clear that we want and need electricity in the container. Just how and how much is not clear yet. In the following, I will consider our rquirements and different apsects and constraints of the electrical installation to hopefully come to a conclusion. This is a rather dry article with a lot of numbers – so beware …

Here is what we know (or at least think we know):

  1. The truck has a 24V system
  2. Charging any “leisure” batteries via the truck engine on a regular basis does not seem to be a good idea, as the fuel consumption is already 33l/100km without the container (that makes an astonishing 8.56mpg in the UK)
  3. It is a EURO0 diesel so we will not be able to get into all the cities (regardless of its problematic weight, length, height and width anyway).
  4. Solar panels are still no real option (most of the time too way up in the North)
  5. Charging from an EVSE might not always be possible as most of these EVSEs are for cars and do not have space for trucks
  6. We want to be able to cook and wash in the vehicle
  7. We will have a 2kW diesel heater
  8. We will have a 900W single phase petrol generator
  9. We will be using Eve LF280K cells
  10. The inverter must at least provide 2'250VA or 1'800W (concurrently, but not neccessarily on a single phase)
  11. (optional) We would like to have 3-phase power in the container (as the cabling is already in place) – but also we know we would only use it very seldomly (such as for welding, then we need at least 11A per phase)
  12. We would like to be able to charge 60% of the batteries (from 20% to 80%) within 3h
  13. We will be using Victron MultiPlus-II (as we do not 2 separate AC inputs)

Here is a list of devices needing electricity:

  1. Refrigerator (able to run on 12V DC/24V DC or 230V AC)
  2. Microwave (1'000W)
  3. Water heater (immersion heater with 1'000W or 2'000W and/or kettle with 2'000W)
  4. Table grill (1'250W)
  5. Steam cooker (450W/900W)
  6. Bread baking machine (600W)
  7. Coffee machine (1'150W)
  8. Washing machine (750W)
  9. Water pressuriation system (850W)
  10. Computers peripherals (USB-C charging with 36W via AC or DC, or 60W AC)
  11. Lights (12V or 24V DC)
  12. Water pump (12V or 24V DC)
  13. Fan (12V or 24V DC)
  14. Diesel heater (12V DC)
  15. Starlink (60W AC, possibly 48V DC)
  16. Infrared heating panel (150W AC)
  17. Battery charger (12V/24V DC or 230V AC, depending on model)
  18. Other USB powered and/or chargeable devices (via 12V/24V DC or separate 230V AC charger)
  19. built-in 6t winch (powered by engine)
  20. (optional) electric shower (8'000W)

Sizing the electrical installation comes with a number of additional constraints:

  1. The crane in the workshop garage can lift up to 500kg
    this mean, all batteries, inverters, washine machine and water tanks must be less that weight
  2. No single battery can charge or discharge with more than 140A
  3. We can only charge from EVSEs with a Type 2 connector

A 12V system is very quickly out of the picture (and the largest and only MultiPlus-II with 12V is a 3’000VA system). Besides, the truck has 24V system anyway. So it is either 24V or 48V. Here is an overview of all current 24V and 48V MultiPlus-II models and their charge and discharge values:

MultiPlus-II 24V and 48V

Let’s first evaluate a 24V system:

Combination of 24V batteries and invertes
  1. 1* 8s battery
    • Capacity is likely to be too small
    • Single battery is not redundant
    • 1*3’000VA can draw too much discharge current
    • 1* 5’000VA can draw too much discharge current
  2. 2* 8s battery
    • 2* 3’000VA can draw too much discharge current
    • 1* 5’000VA possible
  3. 3* 8s battery
    • 1-phase charge requirement can only be met with EVSE 7kW 32A Type 2
    • 3* 3’000VA can draw too much discharge current
    • 2* 5’000VA can draw too much discharge current
  4. 4* 8s battery
    • 1-phase charge requirement can only be met with EVSE 7kW 32A Type 2
    • 4* 3’000VA can draw too much discharge current

So, in a 24V 1-phase system only the 5'000VA inverter would be possible with either 2 (14’336Wh) or 4 (28’673Wh) batteries.

For a 3-phase setup to support our Kemppi Kempact 253A we would need at least 4 batteries and 3* 5'000VA inverters.

And now let’s have a look at a 48V system where we have a couple of more inverter options:

Combination of 48V batteries and inverters
  1. 1* 16s battery
    • Single battery is not redundant
    • 2* 3’000VA inverters needed
    • 1* 5’000VA inverter possible
    • 1* 8’000VA can draw too much discharge current
    • 1* 10’000VA can draw too much discharge current
    • 1* 15’000VA can draw too much discharge current
  2. 2* 16s battery
    • 1-phase charge requirement can only be met with EVSE 7kW 32A Type 2
    • 3’000VA not as 3-phase setup feasible (otherwise 6 devices necessary)
    • 8’000VA only as 3-phase setup, but then too heavy
    • 1* 10’000VA possible
    • 1* 15’000VA can draw too much discharge current
  3. 3* 16s battery
    • 1-phase charge requirement cannot be met
    • charge requirement can only be met with 3-phase EVSE (16A or 32A) Type 2 (11kW+)
    • 3’000VA possible, but too heavy with combined battery weight
    • 5’000VA possible
    • 8’000VA only as 3-phase setup, but then too heavy
    • 10’000VA only as 3-phase setup, but then too heavy
    • 15’000VA possible
  4. 4* 16s battery
    • batteries too heavy
    • 1-phase charge requirement cannot be met
    • charge requirement can only be met with 3-phase EVSE (16A or 32A) Type 2 (11kW+)
    • 3’000VA too heavy with combined battery weight
    • 5’000VA too heavy with combined battery weight
    • 8’000VA only as 3-phase setup, but then too heavy
    • 10’000VA only as 3-phase setup, but then too heavy
    • 15’000VA only as 3-phase setup, but then too heavy

So, this leaves us with really 3+2 choices:

  1. 2* 8s (14’336Wh) batteries in a 1-phase system with a single 5’000VA inverter
    • Battery and inverters would weigh roughly 140kg
  2. 2* 8s (14’336Wh) batteries in a 3-phase system with three 5’000VA inverters
    • Battery and inverters would weigh roughly 250kg
    • Not possible for 3-phase welding
  3. 4* 8s (28’672Wh) batteries in a 3-phase system with three 5’000VA inverters
    • Battery and inverters would weigh roughly 310kg
  4. 1* 16s (14’336Wh) battery in a 1-phase system with a single 5’000VA inverter
    • Battery and inverter would weigh roughly 140kg
  5. 2* 16s (28’672Wh) batteries in a 3-phase system with three 5’000VA inverters
    • Battery and inverters would weigh roughly 310kg
    • 3h on a 1-phase 16A Type 2 would charge about 38% (a 60% charge takes 4.7h)

From there, we can narrow this down even further:

  1. 1-phase system: 24V, 2*8s
    • Price: batteries 2* 1’364GBP = 2’728CHF plus inverter 1* 1’359GBP total = 4'087GBP
      • Con: 24V MultiPlus-II are considerably more expensive (than 48V)
      • Con: only have the capacity
      • Con: cannot run electric shower
  2. 3-phase system: 48V, 2* 16s
    • Price: batteries 4* 1’364GBP = 5’456CHF plus inverter 3* 812GBP = 2’436GBP total = 8'802GBP
      • Con: charge requirement can only be met with 32A Type2 on 1-phase
      • Con: additional 48V|24V DC-DC converter required
      • Con: heavier, 300kg+
        Con: higher self-consumption in 3-phase configuration

So – drum roll – my conclusion: for roughly double the money in a 48V we would get double the capacity and triple the charge and output power and pretty much can do everything we want the system to be able to do.

The 3-phase system can be reconfigured to a parallel 1-phase system, so we would even be able to use an electric shower (though very unlikely – we have our mobile shower). We can either charge 1-phase or 3-phase and have a longer window of electric autarky. And for most of the time we would leave the system in a 1-phase single device InverterCharger configuration. And additionally, for charging the other 2 devices would bet set to ChargeOnly (but be configured independently configured from each other).

The exact setup I will have to layout some other time, but right out of my head I would think of the following components:

  1. External power in with CEE 16-5, CEE32-5, CEE32-1, CEE16-1 and Neutrik PowerCON True1 TOP (the more the better)
    connected to an ATS
  2. AC out from MultiPlus-II connected to ATS
  3. Orion-Tr 24V|48V DC-DC converter
    charging from alternator (though not the norm)
  4. Orion-Tr 48V|24V DC-DC converter
    as power supply: to support 24V loads in the container
    as charger: as an emergency charger for the truck batteries
  5. Lynx Power In, Distributor
  6. Venus OS with Raspberry PI for RS-486 and DVCC

So, in case our Saurer ever gets finished – at least I know how to do the electricity …

Electric Installation in our Toyota HiAce 1994

Now, that we got our Toyota HiAce we thought it might be a good idea to add more power to the vehicle: in form of an 8s EVE LF280K LiFePO4 battery and a Victron MultiPlus Compact 24/1600/40-16 inverter/charger. In the following, we describe our setup and the reason why we built it like this.

The Requirements

  1. The sustained output power of the inverter must be over 1'200W.
  2. Charging via AC via EVSE or generator must be possible.
  3. Charging via alternator must be possible (but is not the norm).
  4. Charging of 60% of the battery (from 20% – 80%) via AC should take less than 180min.
  5. The installation should use the minimum amount of space possible.
  6. We should be able to use our existing Eve LF280K cells, thus limiting the overall current to 140A.
  7. As the vehicle will not have a diesel heater, it should be possible to run a 150W infrared heater for at least 3 * (4+2)h = 18h (^= 2'700Wh).
  8. In addition, the battery should be able to run a refrigerator with an average power consumption of 50W for at least 72h ^= 3'600Wh (next to other power consumption).

Design Considerations

  • With a maximum current of 140A and a cable run length of 1.5m, we should plan with a cross section of at least 35mm2.
  • Basically, with Eve LF280K cells we have three choices regarding the battery size:
    • 1* 4s (“12V”) Configuration
      4 * 3.2V * 280Ah = 3'584Wh
      This would lead to a required nominal AC charge power of at least 716.8W/h and a charge current of at least 56A/h.
    • 2* 4s (“12V”) Configuration
      2* 4 * 3.2V * 280Ah = 7'168Wh
      This would lead to a required nominal AC charge power of at least 1'433.6W/h and a charge current of at least 112A/h.
    • 1* 8s (“24V”) Configuration
      8 * 3.2V * 280Ah = 7'168Wh
      This would lead to a required nominal AC charge power of at least 1'433.6W/h and a charge current of at least 56A/h.
  • The Victron MultiPlus Compact xx/1600VA inverter/charger provides enough sustained power output (while being smaller than the non-Compact edition). Depending on the voltage of the battery, this will slightly impact the amount of charge current.
  • To charge the battery via the alternator we would need a DC/DC converter that depends on the battery configuration as well (either 12-12 or 12-24). So, let’s have a look at the battery first.

1* 4s (“12V”) Configuration

The smallest, lightest and cheapest configuration. But capacity requirements regarding the fridge are only fulfilled, if there are no other loads. In addition, the discharge current is relatively high (scratching the maximum discharge rate of 0.5C).

2* 4s (“12V”) Configuration

More complex setup, as each battery needs a separate BMS, which leads to the need of an aggregator for both batteries to correctly report SoC and calculate CCL and DCL. In addition, more cabling and fusing is required (and probably to a large bus bar). Comes with the advantage of having a redundant battery in case a single battery fails. Most expensive configuration.

1* 8s (“24V”) Configuration

Custom battery build needed, as there is not enough space for a typical 2 * 4 cells setup behind he seats. But, only a single BMS and thus less wiring is needed. Comes with a slight disadvantage of not having native 12V from the battery. This is actually not an isse, as all our DC devices also accept 24V. Cells can better balance voltage differences across a single 8s bank.

The Setup

In the end, I decided for the 8s configuration, due to less complexity. Splitting the 8s configuration across two cell blocks seemed to be an acceptable compromise.

As a regular MultiPlus 24/1600/40-16 would not fulfill my AC charge requirements, I had to decide to either add a second MultiPlus or to add a dedicated charger. I opted for a Phoenix Smart IP43 Charger 24/25 instead of a second MultiPlus. The MultiPlus in parallel would always consume 10W though most of the time I would not need the output power. Whereas, the Phoenix would only need power, when connected to AC. And reconfiguring the MultiPlus every time I charge was not an option for me. And yes, I lose redundancy – but also save some money (Phoenix is much cheaper). So, in the end the nominal charge power is 40A + 25A = 65A, which lets me charge at 1'560W reaching 60% within 165min.

The HiAce comes with a 70A alternator, so I chose a Orion-Tr Smart 12/24-15 DC-DC Charger. With this charger, I could run the engine in standby and still have the car heater running. And this is probably the predominant use case (if charging via alternator at all).

For the DC bus bar I went for a Victron Lynx Distributor, so I could use and install MEGA fuses. Having a 1’000A bus bar seems certainly overkill, but a separate bus bar and fuse box that accepts 35mm2 cable and MEGA fuses would be not be much smaller.

I changed the existing AC inlet of the HiAce to Neutrik PowerCON True1 TOP (congrats to the marketing department, I am still amazed how this name rolls of the tongue) and installed 2 Siemens compact 16A C RCBOs (external AC in, internal AC out). I am aware that theoretically I could support more than 16A on the internal AC out (via PowerAssist). If ever needed, I can replace the RCBO with a 20A version.

I added a VE.Bus Smart Dongle to the MultiPlus and opted against a complete (Raspberry-based) GX installation. The reason, I keep a USB MK3 with me anyway (in case I need to reconfigure the MultiPlus) and still have (Bluetooth) access to the most important settings and information of the MultiPlus. With the GX, I would to be running a WiFi hotspot (and consuming more energy as well). The disadvanage of not being able to use DVCC with information from the BMS is clear to me and accepted.

I selected a B2A8S20P JK-BMS that has an integrated 2A balancer and an RS485, CAN and heat port. In case, I ever add a GX device, I am still able to connect them and use DVCC.

The Specs

  • Nominal power (“capacity”)
    8 * 3.2V * 280Ah = 7'168Wh
  • Maximum discharge power 1’600VA (1'280W, capped by the inverter)
    with a maximum current of 80A/63A/55A (at 2.5V/3.2V/3.65V)
  • Maximum AC charge power 1'560W
  • AC Charging from 20% – 80% in 165min
  • Maximum DC charge power 360W
  • MultiPlus self-power consumption 10W

The Build

As mentioned before, due to space constraints I had to split the battery in 2 parts (with each having 4 cells). Instead of using utz RAKO boxes I used 12mm (sanded) plywood which I did not screw together but tied down with a banding/tensioning tool and a ratchet strap. With this setup, I can easily access und disassemble the cells if needed, while still having a sturdy case. Both cell blocks are connected with a (blue) Anderson SB175 connector.

The BMS itself is mounted to the side of one of the cases (I took extra care to use short screws, in order not to drill into the cell casing). I used M6 Weidmüller 35mm2 90° angled compression cable lug to get the wire away from the BMS and into the bus bar. All other compression cable lugs are DIN 46235 from Klauke (M6 35mm2 on the cells, and M8 16mm2/35mm2 on the bus bar).

The AC and DC wires are all Eland H07RN-F (except for the last two points):

  • Charger to bus bar, battery to bus bar: 35mm2
  • Cell block to cell block: 2 * 35mm2
  • Alternator to DC-DC converter, DC-DC converter to bus bar: 16mm2
  • External AC in to RCBO, RCBO to inverter/charger (both directions), RCBO to internal AC out: 3G2.5mm2
  • For the balancer cables on the cell blocks I used WAGO 221 inline splicing connectors with levers and bullet connectors with 2.5mm2 wire and M6 ring terminals.
  • For the connection of the Inverter/charger to the bus bar, I used the Victron installed 25mm2 welding cables.

Images

The installation is barely visible behind the seats
View from the back with preliminary wiring
Connection of cell blocks with SB175 connectors, cell block 2 and DC-DC converter
Lynx Distributor with cell block 1
Inverter/charger with space for second charger and cell block 2 (left)

Note: the Phoenix charger is not visible on the images, as I am still waiting for it to be delivered.

Charging via EVSE

Conclusion

We now have more than 7'000Wh of additional energy without losing any storage space for roughly 2'850 CHF/2’500 GBP (parts without labour). We can survive an extended weekend of 72h without recharging while still being able to enjoy amenities as using a coffee machine, heating and refrigerator. In case of longer periods of usage, we can recharge at any EVSE, or via shore power. And in emergencies, we can also charge via our Honda EU10i or via the alternator of the vehicle.

The battery is placed directly over the engine which helps in cold weather conditions to easily warm up the batteries to a chargeable level.

The installation can be monitored via Bluetooth (Victron Connect and JK-BMS app).

Building a battery case for a 4s Eve LF280K configuration

Based on our Eve 8s design, I made a sketch for a 4s 12.8V battery, which I could later connect to a Victron MultiPlus Compact 12/1600/70-16:

Wooden case for the 4s Eve LF280K battery

Again, this battery has a wooden inner case and sits inside a utz 400mm x 300mm x 325mm RAKO container.

There are a few differences however:

  1. There is no space for fuses inside the container
    (so it is more like a traditional battery);
  2. all bus bars are “bent” and not straight
    (we need three 35mm2 pairs, so six cables altogether);
  3. main positive and main negative are on the opposite sides of the cells;
  4. I use a JK-BMS B2A8s20P without soldered cables but with dual M6 threads
    (so I can use 35mm2 cables all the way).
utz RAKO 400mm x 300mm x 325mm container with wooden frame

To cut the plywood in an efficient way, I used a web site called cutlistoptimizer which gave me this result:

Cutting suggestion by https://cutlistoptimizer.com/

For this build, I planed all the boards after cutting, before putting in the cells. With this, I hoped to minimise the chance of any particles on the board damaging the cell insulation.

And for the small board at the short side of the case, I did also use 20mm plywood, but planed it several times until it I could just slide it in.

This is how the wooden case looks with the cells and insulation boards (shown in red):

Top view: battery cells with depicted insulation boards (shown in red)

Note: when using a JK-BMS I found it important to have the main negative connection point on the upper left (or lower right). Only with this orientation it was (relatively) easy to connect the cell to the BMS.

BMS connected to cells

It needed some fiddling to get the main negative cable pair to the BMS and the main positive cable pair out of the frame, as we can see from the image above.

The connection to the individual cells are fed through WAGO 221-2411 2 conductor inline splicing connectors. The holes into the top board were done with a forstner bit and a jigsaw. This version of the BMS can be fixed with four screws to the board (so no need for wire straps as with the 24s version).

Again, instead of a display I just used the pluggable power button that is connected to the display port of the BMS to power on and off the device.

In the end, I added Anderson SB175 connectors and 1383 (2AWG) contacts to both pairs and connected them to the inverter.

Battery connected to inverter

Some more details

  • All 35mm2 cables are Eland H07RN-F flexible rubber cable;
  • compression cable lugs are Klauke M6 35mm2 DIN46235;
  • cell contacts were secured with M6 serrated washers and M6 16mm steel bolts;
  • BMS threads B- and P- were secured with M6 lock nuts to M6 16mm steel bolts (with the bolt upside down);
  • cell wires from the BMS were fitted with uninsulated ferrules;
  • cell wires on the positive cell poles were fitted with ring lugs and a 2.5mm2 hookup wire;
  • I added handles to the SB175 connectors to facilitate disconnecting the cable pairs;
  • I added dust covers to the SB175 connectors;
  • all compression cable lugs and the SB175 were crimped with a Hilti NUN54-22;
  • all cable lug connections and Sb175 were heat shrinked;
  • I added 2*35mm2 cable pairs with SB175 connectors to the inverter by replacing the existing 35mm2 welding cable with M8 lugs (you still need M8 lugs on the inverter positive and negative terminals).

Things to improve next time

  • Mount the SB175 connectors to the outside of the container
    With this the lid can be closed and the cables and BMS are better protected against pulling;
  • add 3A inline fuses to the cell wires;
  • use 45° angled cable lugs for main positive and main negative to make it easier to get the wires routed outside the container;
  • feed an additional wire pair for the voltage sensor from the main positive outside the container to be able to connect it to the inverter (but I am not too sure about this, as I think the voltage drop on the 2*35mm2 connection is neglectable – it might better to add a temperatur sensor to the main positive):
  • maybe add protective wire sleeves to the SB175 connectors (but they are quite expensive):
  • add a Victron MK-3 USB-C interface with RJ-45 cable into the case (to be able to restrict AC power on the inverter).

What did it cost?

Cost calculation for the 4s battery including case and inverter

Summary

This case is not as complete as the 8s version – due to its form factor. Neither the inverter has an RCBO nor the battery has a DC MCB. This has to be added separately (incurring additional cost and space). As written above, the 4s version is more like a traditional battery. However, the form factor is quite compelling; 3.5kWh in 400mm x 300mm x 325mm case. Especially in combination with the compact edition of the Victron MultiPlus. And the cost (as always without labour) is very reasonable, as well.

The inverter delivers 1200W constant power – in my opinion, enough for a small and mobile electricity build. Runnig a Krups Inissia Nespresso machine is not a problem, and boiling water with our 1000W immersion heater neither. Worst case, you could also run a 300W infrared panel heater for more than 11 hours.

One drawback of the inverter is probably the relatively small charger. With 70A at 12V it can only charge the battery with around 840W. This is certainly not the problem of the battery which would support charging up to 1344W.

Charging a leisure battery at a Tesco Superstore podPOINT

Some time ago, I wrote about charging leisure batteries at EV charging stations. Today, I was charging at the Tesco Superstore in Wick and got a tip from a neighbouring EV car driver: when you disconnect and reconnect your EV charger within 15min, charging is free of charge.

So, I gave it a try – and it worked. I topped up my battery with my CCS Type2 Neutrik adapter and I was not charged a penny!

Free charging at Tesco Superstore podPOINT

Why they do this is not totally clear to me. But hey, I am ok with that.

In the video below you see our Toyota “2er” Hiace 1994 retrofitted semi-electrical vehicle being charged at the podPOINT Ralf-Milo:

Charging a 24V Eve 8s LF280K battery at an EV charging station

Building a battery case for an 8s Eve LF280K configuration

In one of our previous articles, we stated that, due to power, weight and size, we would rather go for a 24V 8s (280Ah) battery configuration instead of 48V 16s.

However, there are relatively few battery cases for 8s battery packs that fit our Eve LF280K cells. And they are pricey! So, instead of spending a 500+ USD per case, I was thinking to repeat what others have done before me: build a case myself. And certainly, I took inspiration from various others and commercial kits.

So first, here are my requirements:

  1. Case must fit 8 EVE LF280K cells including all electronics and cabling such as BMS, MCB, GX.
  2. Battery must be pluggable to the inverter via Anderson SB 175 connector.
    Check: why not use Amphenol sockets/plugs?
  3. Case must not absorp moisture/liquids that would build up from below.
  4. Case must have no external display or buttons (i.e. solid walls).
  5. Cells must be insulated against each other.
  6. Cells must be fixed to the case so the do not fly around when the box is moved.
  7. Battery status should be readable from the box itself (optional).
  8. The case should be usable independant of any BMS.
  9. Battery is meant to be used 1:1 with a single inverter.
  10. Battery must have an integrated MCB that can also act as a mains switch.

Basic considerations

Zerobrain – LiFePO4 – ALLES und noch viel mehr über Lithium Akkus

Of course, there are more questions to be answered. And I took a lot of inspiration and advice from the discussion above and came to these conclusions:

  1. Material
    I will use a 600mm x 400mm x 325mm utz RAKO box
    Fun fact: if you buy the “same” box in Switzerland, it is 2mm higher and one gets 2mm more usable space inside.
  2. Fire resistance
    The cells should not involve themselves in a “chain reaction” if a cell becomes faulty. The critical temperature of the cells starts at around 90°C. If something is really getting sideways, the resin board will not withstand any of that at all. But as the battery case will be contained either within an aluminium container or directly inside in an aluminium box, I will take that as a mitigation (only the brave).
  3. Moving and lifting
    the cells should have a weight of roughly 8* 5.5kg = 44kg;
    the 20mm resin board weight roughly 3.34kg (13.67kg/m2);
    BMS, MCB, cables, lugs etc might add another 3kg;
    the Rako(R) box has a weight of 2.35kg;
    resulting in a total weight of 52.69kg – which certainly is over the official limit of 32.5kg to be lifted by a single person – but still doable if one has to.
    For moving the battery box around I have a trolley where the RAKO box just fits on.
  4. Compression
    Initially I thought, I would *have* to compress. But according to the above video, it seems the is only needed (or recommended) during the initial charging of the cells (to minimise gas bubble inside the cells). And from then on, it is not *required* for a safe operation of the battery, but instead might contribute to an extended cell life – how much? we do not know.
    So, I will probably only slightly compress the cells by placing them firmly into the frame inside the box.

Layout

So, I started with some sketches in FreeCAD and came up with the follwoing layout.

It should be possible to fit 8 EVE LF280K batteries in a 600mm x 400mm x 325mm RAKO box and still have space for the electronic components. Inside the plastic box there is a wooden structure, so the weight of the batteries is better balanced (the plastic floor might like this).

Batteries will be insulated against each other and fitted with sponge strip. Internal cabling will be fed through the lid where the BMS is mounted on. Cables to the outside (VE.Bus, 2*35mm2 DC, 2* 3-core AC) will be fed through the side wall.

Empty utz RAKO box 600mm x 400mm x 325mm
Box with batteries and electronic components on top
View of frame with cells inside box

BMS Cabling

I am going to use a 150A JK-BMS for the battery which comes with 2 pairs of 7 AWG wiring (approx. 10.5mm2 per wire). As I am going to have a mximum current of 150A (at 20V; or 117A at 25.6V) this will result in a voltage drop between 0.1% and 0.2% on the BMS cable. For the rest of the cable to the battery I will use a 50mm2 that results in an additional max 1% of voltage drop. The actual connection to the batter will be done via an Anderson SB 175 connector.

The individual BMS cell wires will be fed through a WAGO TOPJOB S 3-conductor through terminal block (with a separate fuse) (or I use a WAGO 2-conductor fuse terminal block – don’t know yet). With this I can easily connect and disconnect the individual wires from/to the cells. And with the 3-conductor terminal block if needed, I can later add an additional balancer to the system without having to rewire the cells either.

The cells will be wired in a regular 8s cconfiguration to the BMS. Both voltage sensors will be placed in the middle of the batteries.

Bus bars

My Eve LF280K cells have 2 M6 thread for each pole. The bus bars that came with the cells (cross section is 2mm * 20mm) were not flexible and only suitable for connecting the poles on the long sides. However, with my 8s configuration, I need 4 connections on the short side and 3 connections on the long side of the cells.

So, I created my own bus bars with the help of 2* 35mm2 DIN46235 M6 cable lugs per connection.

Dimensions: short side 30mm + 29mm; long side 30mm + 80mm (cutting at 30mm for the cable lugs to be crimped).

The Build

So, I with this information I started the actual build. And certainly I made some adjustments to the layout. This is what it looks like:

Case with all the cells on one side

As you can see, I moved the batteries to one side. With that I have more space on one end to install a MCB and leave room for cables.

Updated drawing with cells on one side
Wago fused terminal blocks for connecting the indivisual cell wires

All the battery wires are connected to WAGO TOPJOB S 2002-1681 2-conductor fuse terminal block. The fuse I used is a 3A Mini OTO fuse (as the balancer is a 2A balancer).

Connection of the BMS to the cells
Case with cells covered

The BMS rests on a board that can be fixed to the side walls. I intentionally left some space between both boards to have room for the temperature sensors. On the right hand side, we see the BMS wires connected to the terminals. With this it is easy to see which cable goes where. I could have cut the BMS wires. Maybe I will do this later.

As the DC cables were quite stiff, I used a screw to support a 90° angle on the cable going out of the box. The screws are fitted with electrical insulation wire. Let’s see how long this holds up.

Victron MultiPlus-II 24/3000/70-32 with Neutrik connectors

The inverter now has Neutrik panel connectors. I used a 24mm and 29mm hole saw for this. With this I do not have AC cables hanging out of the inverter. The connectors are rated for 16A (VDE) or 20A (UL). I set the maximum current on the inverter settings (as the inverter supports up to 32A which is beyond the capabilities of the socket).

Of course, the DC cable is still present. Maybe I can install a socket for that as well.

Inverter with battery

Above you see the “final” case. The battery is connected via Anderson SB 175 to the inverter. The battery cables fits into the case when not in use.

Not seen on the picture. The inverter has been fitted with a Siemens 16A RCBO for AC out. And inside the case is a non-polarised Thomzn 125A DC MCB.

The BMS charge and discharge current is set to 125A (though the inverter only supports up to 70A, and in reality only seldomly charge with more than 63A).

The Specs

With this inverter/battery duo, I have a system with a nominal power of 7168Wh that can deliver 2400W of constant power (below the 0.5C rating of 140A). Down to a cell voltage of 3V I can make use of the full power (then running at 125A). As the current minimum cell voltage is configured to 2.55V I always have a minimum power of 2550VA (or 2040W). But in reality I have never seen all the cells at the minimum voltage at the same time.

The case weighs around 51+kg and the inverter is around 20kg.

The maximum charge current of 70A @24V result in a maximum charge power of 1680W. So theoretically it takes slightly over 4h to fully charge the battery. In reality we can expect the battery to be charged around 20% per hour. A real life test shows that within 3h we can charge from 20% to 85%.

The Aftermath

What went well, what went wrong? Here are some of my thoughts:

  1. The case looks and feels solid when lifted. So I really think the weight will not by a problem, though the RAKO box is not certified for that weight. I think, I could have used even thinner plywood and that would have saved some additional space.
  2. Moving the cells to the right made more space on the other side, so I was able to fit the DC cable with the Anderson plug into the case as well (in addition to a MCB).
  3. Creating the bus bars was relatively easy. The cable is still quite stiff. And the longer bus bars bend over the edges. That is why I had to add an extra piece of board to the sides.
  4. The JK BMS wires are very fine strained and hard to get into the lugs (it literally took me over an hour to connect the 4 wires).
  5. The addition to the fused terminal blocks makes the cabling much cleaner. But the WAGO terminals are not cheap.
  6. Unfortunately, with my JK BMS the cables are soldered to the BMS and cannot be replaced. I think 2* 7 AWG is relatively small/thin. I would have preferred 2* 35mm2 (as for the bus bars). With the new JK BMS model there is the option to connect my own cable to the BMS.
  7. This version of the BMS comes with a power button, making it much easier to turn it on than before. No need for a DC power source with higher voltage than the cells.
  8. Fitting the cells into the case (with some compression) was easier than I thought. I used some insulation board between the rubber and the board to push it between the frame and the cells.
  9. I actually do not use the RS485 option for this standalone installation. The BMS seems to take care of the the charge and discharge currents. And if I have really have to know the SOC, I connect via bluetooth to the BMS directly. And I only use the VE.BUS connection with the VictronConnect App when I want to change or limit the AC input current. For this I use the VE.BUS bluetooth dongle.
  10. Having the Neutrik connectors makes it much easier to disconnect the inverter when moving.
  11. Regarding the Neutrik panels on the inverter. I could not fit them in the holes where the AC wirng would normally go through, as the cable clamps were in the way. So I had to use the space between the ventilation slots. It is quite fiddly to get them screwed onto the cover. I used a 24mm and 29mm hole saw with M3 x 20mm hex bolts and M3 hex nuts for it.
  12. The integrated RCBO saves me from having a separate elecitrical panel.
  13. Maybe I change the DC connectors to Amphenol sockets as the SB175 is quite bulky.
    (update on this: probably not; they are quite expensive and only have 50+ connection cycles guaranteed; plus, it is not specified if they can be switched under load)

The cost

Here is a rough estimate of the accrued cost for this build:

Estimate for the material used for this build

If I only count the cost for the case (excluding cells, inverter, BMS) I come up with approx. 400CHF/450USD/350GBP/400EUR. So it seems, that I could have bought a prebuilt case for nearly the same amount of money, right? True. But … with this case, I have the exact dimensions that I want and with much less weight. And with the exact components I want. Plus, I can repair (if needed) everything by myself, as I completely know how it was built.

Let’s see what I will change on the next case I build.

Updates

Here are some hints and thoughts that arose after I wrote the article.

  • Getting the cells into place
    I used a 12mm marina plywood with an extra sheet of insulation board, so the board could “slide” (be pushed) between the frame and the cell. I used a planer with a depth of 0.5mm to cut away just as much so I could just firmly squeeze it in.
  • Frame and any wooden part in general
    It is a good idea to grind the surface of the wood facing the cells to remove any pieces sticking out that could damage the very thin insulation of the cells.
  • Insulation boards
    At first, I cut the insulation boards from a 250mm x 500mm board. I found it the easiest way to use a drawing pin to mark the cut and then bend it bothways. But this means we have to do 5 cuts for getting 3 boards – that takes time. So, I now have precut 170mm x 200mm insulation board with rounded corners. Much easier to handle.
  • Fixing the M6 bolts to the contacts
    I used an insulated torque ratchet wrench (4Nm) to tighten the bolts to the contact.
  • For the cable lugs I used Klauke M6 35mm and 16mm DIN 46235 cable compression lugs.
  • For the cell voltage sense cable I used 2.5mm wires (I know, 1.5mm would have been more than enough, but it was the only wire size I had). The JK-BMS supplied voltage sense cables were fitted with uninsulated ferrules, so they would fit into the WAGO 2002-1681 terminal fuse blocks.
  • Regarding cost
    The other day, I saw Pylon US3000 3.55kWh Lithium Battery being sold at CCL Components for 860.06GBP (excl. VAT). This includes a 19″ rack metal case, a BMS, connectivity and the cells and equates to roughly 269 GBP/kWh. Quite a bargain! Why making your own battery (case) any more?
  • I will replace the 24s BMS with an 8s version so I can use 35mm2 cable all along. Plus, I will use two pairs of 35mm2 cables from the inverter to the battery. That also means, I will have 2 separate 63A DC MCBs instead of a single 125A MCB.

Cutting the plywood

I found web site that offers help in cutting rectangles in a more efficient way that I could come up with: Cut list optimiser. The board for the case could be cut like in the image shown below.

Cutting suggestion by https://cutlistoptimizer.com/

Building a Neutrik powerCON True1 TOP distribution from a LeGrand Plexo junction box

Recently, when I converted most of my electrical sockets and connectors to Neutrik powerCON True1 TOP, I was looking for a Neutrik power distribution. After some failed tests to build a box myself from an junction box, I found a product called Mini Brick from an italian company called Valentini which was sold via Distribution Zone in the UK for a retail price of 145 GBP (174 GBP incl VAT).

Neutrik Mini Brick, image copyright Valentini, https://www.powerboxsyntax.com/
Neutrik Mini Brick, image copyright Valentini, https://www.powerboxsyntax.com/

The box is essentially a 6-way (and not 7-way as shown above) power distribution rated up to 3500W (nearly 16A @ 230V) and has a red status light to indicate if it has power.

Build quality is very good (metal or hard plastic case, rubber coated); and the price is also understandable, as the chassis connectors alone would cost around 60 GBP. However, I was not totally happy with it due to is relatively massive form factor: L80mm x W75mm x H300 mm plus connectors.

So, I had to go back to the drawing board. And I found a junction box from LeGrand, a french manufacturer, without any membranes or cutouts with these dimensions: 105mm x 105mm x 55mm (and an IP 55 rating). In this box I should be able to install one Neutrik NAC3PX duplex connector and four Neutrik NAC3FPX-TOP (female) connectors.

To cut the holes for the chassis connectors into the case, I used a Hilti 30mm hole saw with my Wabeco drill stand. Drilling the duplex chassis connector obviously needed 2 holes and a cutting away some excess plastic (later on I found out that a 25mm diameter is better suited for the smaller part of the duplex connector):

Opening for the Neutrik NAC3PX-TOP duplex chassis connector
Opening for the Neutrik NAC3PX-TOP duplex chassis connector

Note: one might be even able to use 29mm and 24mm holes, see the detailed drawing – maybe I try this next time.

To mount the chassis connectors onto the box, I used M3 screws and hex nuts (I could not find TX versions) which I drill with a 3mm Hilti HSS-Cobalt drill (yes, overkill – but the only drill I had at hand). Unfortunately, the screws were a slightly too short, so it was a little bit of fiddling to get the hex nuts onto to the screws.

Neutrik NAC3FPX-TOP front view, drawing copyright Neutrik, https://www.neutrik.com/en/product/nac3fpx-top
Neutrik NAC3FPX-TOP front view, drawing copyright Neutrik, https://www.neutrik.com/en/product/nac3fpx-top

After all the Neutrik connectors were installed, I wired them to a 5-way Wago 221 COMPACT series splicing connector (221-415) with fully insulated blade receptable connectors (1.5mm2, 0.8mm, 6.35mm) to the socket and with 1.5mm2 ferrules to the clamp.

Here a quick list of tools I used:

Tools used for the build
Tools used for the build

After assembly I did a final connectivity test to ensure all wires (L, N, PE) were correctly connected. As the duplex connector has a different wiring layout, it is easy to mix things up (PE is in the middle and not at the side).

5-way Neutrik powerCON True1 TOP distribution in a LeGrand Plexo junction box
5-way Neutrik powerCON True1 TOP distribution in a LeGrand Plexo junction box

The end result is not as sturdy as the Mini Brick, but much lighter and smaller. And if I ignore the amount of labour I put into the build, this box is certainly much cheaper.

Video: 5-way Neutrik powerCON True1 TOP distribution box made from LeGrand Plexo

And as usual: electrical installations can be dangerous – only have them performed by qualified personnel.

30 Days into using the Victron MultiPlus 12/1600/70-16 inverter and a Liontron 12V 80Ah with our Swift Sprite Caravan

The Caravan we got last year did not come with an inverter, so getting coffee in the morning or running a microwave was only possible when our main generator was running. And the installed battery for 12V support had a rather small capacity. This was clear to us from the beginning, as we eventually wanted to connect the Caravan to our EVE 280Ah cells.

But since we got our Starlink internet and our router did not seem to run easily on DC power, we needed -in addition to the temporary morning AC coffee spike – a more permanent AC solution.

So, I grabbed an existing Liontron 12V 80Ah battery that was sitting on the shelf along with a Victron Energy MultiPlus 12/1600/70-16 charger/inverter and connected the inverter AC Output to the CEE16-1 AC input of the caravan and the inverter AC Input to one of the phases of my JCB G20QS generator (of course, all via Neutrik powerCON TRUE1 TOP connectors and H07RN-F3G2.5 cable).

For the connection between the inverter and the battery I used a 35mm2 cable and Klauke DIN 46235 compression cable lugs on one end and insulated ferrules on the other end. In between, I added Anderson SB 175 connectors with 1383 lugs for quick disconnects and crimped as shown here. For the fuse I used a Schneider Electric 125A DC MCB, as I do not expect higher loads in this setup.

Of course, first I updated the firmware of the inverter and configured it work with the battery:

  1. Setting the AC input to 16A
  2. Setting the battery type to LiFePO4
  3. Setting the charge current to 70A (which is over the recommend amount of 50A, but see below for details)

As I did not want to connect a Cerbo GX to the system, I just used the VictronConnect App. Maybe I add a VE.Bus Smart dongle later on, or I connect some GX nevertheless. Who knows … Until now, it needs a wired connection to the inverter to see its status.

After powering on the generator, I confirmed everything was roughly working as expected. During the first run, the SOC was shown as 100% though the BMS of the battery internal saw it differently. In addition, the reported Amps and temperature were seen differently, as well. So, even that I set the inverter over the recommended maximum of 50A for the battery, the actual charge power was never much higher than the actual maximum).

This is what the inverter saw (100% SOC, 14.05V DC cell voltage, charging at 64A):

MultiPlus charging the Liontron battery via the generator

And this is, what the Liontron BMS reported (76% SOC, 13.8V DC cell voltage, charging at 55.5A):

The SOC as seen by the Liontron battery BMS

In the end, the BMS stopped charging when it thought its batteries were full. And the inverter did not complain. However, I noticed that the cells were really not in balance (with a delta of 200mV between the lowest and highest voltage).

Discharging was ok, as well. However, I soon realised that the 100A discharge current could not be achived in my setup. The inverter tried to draw power and the BMS cut off with a “Discharge over-current” (OCD). SO, still no coffee via our Nespresso machine (and no microwave either, for that matter).

So, what is the take away of all this?

  1. It works and now, I can run the Internet all day.
  2. All in all, it is a relatively simple and quick setup.
  3. The Liontron battery does somehow not live up to its specs (and yes, I know the battery could be a size bigger for what I want to achieve; but I did not want to buy an additional battery for this temporary solution).
  4. It is way cheaper and more flexible than to buy this “off the shelf”.
  5. Maybe, I add a Victron SmartShunt to get a more accurate SOC reporting (as I do not see any other way to integrate the BMS with the inverter).
  6. Charging of the battery is quite fast when running the generator.

Everything Neutrik PowerCon TRUE1 TOP

So, a few already know … In the last couple of days, I finally decided for a “universal” adapter standard to get rid of my UK, Swiss and European plugs and sockets. I looked at different adapters and the winner is:

Neutrik PowerCon TRUE1 TOP. Amazing how this rolls of the tongue …

The connector is a successor to the tried and tested “PowerCon” – but with some advantages:

  1. It supports “hot-plugging” (connecting and disconnecting under load)
  2. It is IP65 rated.
  3. They come in a “L”-version for cables with a larger diameter. But even the normal sized connectors still fit a 3-core 2.5mm2 H07RN-F cable.

It is also a locking connector like the original PowerCon with male and female connectors and good for up to 16A. But they are a little more expensive. Interestingly, Thomann was the cheapest supplier I could find in Switzerland. Below you find a simple overview with the existing connectors and sockets along with their part numbers (taken from the Neutrik web site).

Coipyright and taken from http://neutrik,.com

As you can see, there is no colour-coding for power inlets and outlets any more. Water-proof caps for the (wall) sockets are around 1.50 CHF per cap and therefore relatively expensive.

But what problem was I trying to solve in the first place?

We have AC electricity in our cars, the caravan and the trailers and soon in the barn and shed at the Loch. And we have appliances with UK, Swiss and EU (Schuko, Euro) plugs as well. And a plethora of adapters with the right one always not at hand. It was time to change that.

And the one thing I knew for sure was: I did not want to install UK sockets in the barn and shed. So, my idea was to install some more space-saving sockets. I already had good experience with the original PowerCon connector. However, they are not meant to be switched under load. Something that I definitely wanted to have with my new solution.

I could have sticked to plain Swiss connectors, as most of my appliances are already equipped with it. However, the typical Swiss triple T13 adapters tend to be occupied quite quickly as soon as we use AC/DC adapters or the Schuko fix-adapters. And if you get a quality product from a company like Feller, each triple socket costs around 50,00 CHF to 60,00 CHF. Compared to 3 Neutrik sockets this is way more expensive.

So, instead of researching any further, I quickly made a decision and went for the TRUE1 TOP system (from Liechtenstein). And it seems that I am not the only one with that idea, as I could see from various videos here, here, here and here.

My only real concern is, that after the “true” TRUE1 and the recent successor TRUE1 TOP, there will soon be an even “truer” replacement in the form of another imcompatible connector. But hey, what would one know anyway these days?

So, after last week the first batch of sockets and connectors arrived, this weekend I started with the conversion.

Inside our caravan, I added a couple of Neutrik sockets in the living room. See here:

Neutrik PowerCon True1 Top in our UK Swift Sprite Major 4 EB

I then updated the connections on the Toyota Hilux and relaced all the inputs, outputs and appliances. With this I could get rid of quite some adapters (from and to EU, UK, CH, CEE16-1, CEE16-3 etc).

Cooking with Neutrik PowerCon True1 Top in our Toyota Hilux

So what do I think so far? I am positively surprised.

  • Exchanging the connectors is simple and quick.
  • Even the thick 3-core 2.5mm2 H07RN-F cables fit in the connectors.
  • All the screws in the connectors are Torx (TX).
  • The connectors are not too bulky.
  • The adapters I made (e.g. from UK to Neutrik) are all rated for 16A (or 13A if we reuse the existing UK plugs). Travel adapters like the ones from Skross are typically only rated to 7A or 8A.

So, I will keep changing more and more of my appliances and will resurrect this post when I have news on this …